This section introduces aspects that may facilitate better understanding of the present disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
In a Long Term Evolution (LTE) network, all communications are carried over an Internet Protocol (IP) channel from user equipment (UE) to an all-IP core called the Evolved Packet Core (EPC). The EPC then provides gateway access to other networks while ensuring an acceptable quality of experience and charging a subscriber for his/her particular network activity.
The 3rd Generation Partnership Project (3GPP) generally describes components of the EPC and their interactions with each other in a number of technical specifications (TS). Specifically, 3GPP TS 23.203, 3GPP TS 29.212, 3GPP TS 29.213, and 3GPP TS 29.214 describe the Policy and Charging Rules Function (PCRF), Policy and Charging Enforcement Function (PCEF), and Bearer Binding and Event Reporting Function (BBERF) of the EPC. These specifications also define Policy and Charging Control (PCC) architecture and provide some guidance as to how the aforesaid elements interact in order to provide reliable data services and charge subscribers for use thereof.
As an example, FIG. 1 represents the PCC architecture as defined in FIGS. 5.1-1 of 3GPP TS 23.203 V13.6.0. The PCC architecture includes, amongst other entities, a PCRF in charge of policy control decision and flow based charging control functionalities, as well as in charge of provision of PCC rules to be enforced at the bearer layer; a PCEF which may be embodied in a Packet Data Network Gateway (PGW), a Serving GPRS (General Packet Radio Service) Support Node (SSGN) or the like and in charge of service data flow detection based on filters included in the PCC rules received from the PCRF, as well as in charge of PCC rules enforcement at the bearer layer; and an Application Function (AF) for offering applications.
Regarding the communication between the above PCC entities, as disclosed in 3GPP TS 23.203, PCRF and PCEF communicate through a so-called Gx interface, whereas PCRF and AF communicate through a so-called Rx interface. In particular, the PCRF provides control rules to the PCEF through the Gx interface, whereas the AF provides the description of the media to be delivered at the bearer layer to the PCRF through the Rx interface. Regarding the control rules submitted from the PCRF to the PCEF, these control rules include, although are not limited to, those PCC rules disclosed in 3GPP TS 23.203, and can be provided upon establishment or modification of an IP Connectivity Access Network (IP-CAN) session.
In 3GPP TS 29.212 V13.4.0, the Gx interface is particularly defined for provisioning and removal of PCC rules from the PCRF to the PCEF and transmission of traffic plane events from the PCEF to the PCRF. The Gx interface can be used for charging control, policy control or both by applying Attribute Value Pairs (AVPs) to carry policy information.
A policy based on time (which is also called ‘time-based policy’ hereafter) allows an operator to apply a specific control rule, e.g. a PCC rule or an Access Point Name-Aggregated Max Bit Rate (APN-AMBR) value, to a user during a certain time period. For example, according to a time-based policy, a PCC rule for controlling bandwidth of a Peer-to-Peer (P2P) service may be activated to limit the bandwidth of the P2P service for most hours of a day and deactivated to release the limitation for a few hours early in the morning. According to another time-based policy, an APN-AMBR value may be applied to an IP-CAN session for peak hours of a day and another APN-AMBR value may be applied for non-peak hours.
Currently, activation and deactivation of a control rule, e.g. a PCC rule, may be achieved by either of the following mechanisms according to a time-based policy.
In the first mechanism, the activation/deactivation of a PCC rule is completely controlled by the PCRF.
For example, a time-based policy specifies that a PCC rule for limiting the bandwidth of a P2P service shall be applied during a day except an ‘early morning’ period. Then when the ‘early morning’ period starts in the day, the PCRF deactivates the PCC rule which limits the bandwidth of the P2P service, and when the ‘early morning’ period ends, the PCRF activates the PCC rule so that the bandwidth limiting is applied to the P2P service.
Then, in the following day, the PCRF repeats the same activation and deactivation operations when the ‘early morning’ period starts and ends.
A main drawback of the first mechanism is a signaling storm on the Gx interface because the PCRF may need to provide the time-based policy for all users at the same time point.
In the second mechanism, the activation/deactivation of a control rule, e.g. a PCC rule, is controlled by the PCEF.
This mechanism is specified in clause 4.5.13 “Time of the day procedures” in 3GPP TS 29.212 V13.4.0, aiming to avoid the signaling storm on the Gx interface as caused in the first mechanism.
In the second mechanism, the PCRF instructs the PCEF to defer the activation and/or deactivation of the PCC rule. The PCRF may also instruct the PCEF to request a new rule after a certain time period, e.g. Revalidation-Time as defined in TS 3GPP TS 29.212 V13.4.0. In order to do so, the PCRF provides the Event-Trigger AVP with the value REVALIDATION_TIMEOUT and in addition, the Revalidation-Time AVP. This will cause the PCEF to trigger a PCRF interaction to request a PCC rule from the PCRF for an established IP CAN session upon expiration of the Revalidation-Time.
According to 3GPP TS 29.212 V13.4.0, the PCEF shall send the PCC rule request before the indicated revalidation time. The PCRF is expected to be prepared to provide a new policy, as desired for the revalidation time, during a preconfigured period before the revalidation time. The preconfigured periods in the PCEF and the PCRF need to be aligned.
Additionally, APN-AMBR provisioning on the basis of time can also be achieved by using a time-based policy completely controlled by the PCRF. Likewise, when the time is due for a new APN-AMBR, the PCRF may provision the new APN-AMBR in a Re-Auth-Request (RAR) message.
For example, a time-based policy specifies that different APN-AMBR values are applied for peak and non-peak hours in a day. Then according to this policy, the PCRF may cause the APN-AMBR to be limited to 20 Mbps during the peak hours, and cause the APN-AMBR to be increased to 50 Mbps during the non-peak hours.
In the recent 3GPP SA2 #112 meeting, some operators require support of a deferred APN-AMBR in order to reduce signaling on the Gx interface. That is, in addition to providing an authorized APN-AMBR for the ongoing session, the PCRF should also be able to provide an APN-AMBR value that is expected to be applied at a later time point, or provide a list of APN-AMBR values that are expected to be applied at later time points which are actually recurring.